<title>Optical extinction from Raman lidar measurements</title>

Abstract

Lidar can be an effective tool for measuring the optical extinction along atmospheric paths. The Penn State University LAMP lidar recently participated in a series of atmospheric measurements at NASA's Wallops Island test facility in September 1995. The LAMP lidar was operated with the beam pointed along horizontal and vertical paths. This paper discusses the determination of atmospheric extinction coefficients with Raman lidar measurements. Lidar measurements show the presence of aerosol layers in the atmosphere as a marked departure from the expected molecular profile for a Raman lidar signal. The horizontal extinction coefficient can be determined directly from the range corrected slope of a horizontal Raman profile. The vertical extinction coefficient can be determined directly from the range corrected slope of a horizontal Raman profile. The vertical extinction coefficient can be determined by comparing the gradient of the Raman lidar profile with the gradient of the molecular atmosphere. The LAMP lidar has also been used with a bistatic receiver to measure the scattering phase function which can then be used to calculate the aerosol particle size distribution and the optical extinction coefficient. This paper will discuss the experimental method and present several representative examples from Raman lidar measurements. The extinction coefficients determined form the Raman lidar data will then be compared with the extinction coefficients determined from the bistatic receiver data.